valid_Operaters = ("+", "-", "*", "/")

while True:
	num1 = float(input("请输入第一个数>>"))
	while True:
	    operater = input("请输入运算符>>")
	    if(operater not in valid_Operaters):
	        print("无效的运算符！请重新输入")
	    else:
	            break
	num2 = float(input("请输入第二个数>>"))
	result = 0
	if operater == "+":
	    result = num1 + num2
	elif operater == "-":
	     result = num1 - num2
	elif operater == "*":
	    result = num1 * num2
	elif operater == "/":
	    if num2 == 0:
	        print("除数不能为0！")
	        continue
	    else:
	        result = num1 / num2

	print("计算结果为：", result)
input("请按任意键进行下一次运算")
